NOTE - Load Factor in Straight & Level Flight (SnL) = 1
The Question says - Increase in Angle of Attack (AoA) of 1 degree increases CL by 0.1. Therefore change of 3 degree AoA changes CL by 0.1 X 3 = 0.3
CL in SnL = 0.42
CL on experiencing Vertical Gust = 0.42 + 0.3 = 0.72
Now Calculate the % increase in Load Factor (LF) .72/.42 = 1.71
Therefore the increment in LF from SnL is 71%
New LF =( 1 + ( 71% X 1 )) = 1.71
Hope it helps.